Several remedies are hitherto known to prevent bovine leukemia and there are methods for preventing this disease using these medications.
An inactivated vaccine against bovine leukemia is known (see USSR author's certificate No 820,015, class A61K39/12, publ. Oct. 23, 1987) containing the protein fractions p25 and gP70 isolated from the peripheral blood leukemia cells of animals suffering from leukemia.
The obtained antigen-protein immunizing agent with Freund's complete adjuvant in a 1:1 ratio is administered to 1 to 3 month old calves. This immunization is carried out three times at intervals of 10-12 days.
Another inactivated vaccine against bovine leukemia is also disclosed (see RF patent No 2,202,367, IPC class A61K39/12, publ. Apr. 20, 2003), containing virus-containing leukocyte cells of the peripheral blood of animals. The immunization of animals is carried out subcutaneously three times with an interval of 10-14 days. Animals are vaccinated at the age of 2 months to 2 years.
These vaccines, however, have not found wide practical application due to the lack of means of immunological failure correction and the formation of low-titer antibodies.
Various remedies for bovine leukemia prevention are known as well.
In particular, the use of an amber biostimulator (see RF patent No 2,420,275, IPC class A61K31/194, publ. Jun. 10, 2011), polycarboxyethylene (see RF patent No 2,421,184, IPC class 2421184, publ. Jun. 20, 2011), metronidazole and norsulfazole or sulphadimezine (see RF patent No 2,300,883, IPC class A61K67/02, publ. Jun. 20, 2007), ligfol (see RU patent No 2,320,357, IPC class A61K36/00, publ. Mar. 27, 2008) etc. is known.
However, the influence of these preparations on the immune system at leukemia has not been studied and these remedies have found no practical application.
More particularly, metronidazole and sulfonamides have bactericidal rather than virucidal action, which does not allow them to render a specific effect on BLV. Ligfol is a hydrolyzate of natural lignin, humic substances being its active ingredient. Ligfol shows stress-corrector and adaptogenic actions, its injections are painful and cause long-term anxiety of animals. The effect of the amber biostimulator, which is a mixture of succinic acid and Dorogov's antiseptic stimulant (DAS), fraction No. 2, like that of any biologically active drug, has also been studied little and requires additional studies.
The closest to the present invention is the bovine leukemia prevention on the basis of tuberculosis toxoid (see RU patent No 2,396,978, IPC class A61K39/295, publ. Aug. 20, 2010). Tuberculosis toxoid is administered subcutaneously 20-30 days prior to vaccination with an inactivated vaccine against bovine leukemia. This tuberculosis toxoid is obtained (see, e.g., RU Patent No. 2,392,002, IPC class A61K39/00, publ. Jun. 20, 2010) by detoxification of tubercular exotoxins and endotoxins with two detoxifiers, namely, 0.2% formalin solution during 7-9 days at 42-45° C. and 0.5% aethonium solution during 7-9 days at 42-45° C.
However, this method for preventing bovine leukemia uses the mycobacteria destruction products in the whole, rather than the protein fraction isolated therefrom. The degradation product generally contains proteins, lipids, and polysaccharides. Lipids and polysaccharides increase the immunogenic load on the animal organism, change the homeostasis state and prevent a targeted immune response to mycobacteria proteins, which, in the end, reduces the efficiency of such preventive measures and does not ensure lifelong resistance of animals to the disease.